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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Justification for type of information:
see section 13
Reason / purpose:
read-across source
Reason / purpose:
read-across: supporting information
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
The samples were stored deep-frozen (-20°C) until the analysis was performed
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
- Specie: Scenedesmus subspicatus Chodat
- Strain: 8681 SAG
- The algae were grown in the laboratories under standardized conditions according to the OECD Guideline 201.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Test temperature:
20.5 - 23 °C
pH:
8.03 - 8.5
Nominal and measured concentrations:
6.25, 12.5, 25, 50 and 100 µg/l (nominal) the analysed test media amounted to 85.1 - 106.5 % of the nominal values
Reference substance (positive control):
no
Key result
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
43.2 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
22.7 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
biomass

In the lowest concentration tested of nominal 6.25 µg/l, a greater growth inhibition was observed than in the next higher concentration (12.5 µg/l). The reason of this effect is unknown, but obviously not a toxic effect of the test substance, since first in the concentration range of 12.5 to 100 µg/l a clear concentration-effect-relation was determined.

Validity criteria fulfilled:
yes
Conclusions:
Biomass: EyC50 (96h) = 22.7 µg/l
Growth rate: ErC50 (96h) = 43.2 µg/l
Executive summary:

The influence of the substance on the growth of the greenalga Scenedesmus subspicatus Chodat was investigated in a 96 -hour static test according to the OECD 201, in according to the GLP principles. The test was performed at nominal concentrations of 6.25, 12.5, 25, 50 and 100 µg/l. During test duration, the test article concentrations in the analysed test media were higher than 80 % of the nominal values.

Results:

Biomass: EyC50 (96h) = 22.7 µg/l

Growth rate: ErC50 (96h) = 43.2 µg/l

Description of key information

ErC50 (96h) = 43.2 µg/l

Key value for chemical safety assessment

EC50 for freshwater algae:
43.2 µg/L

Additional information